MainActivity页面
package com.example.image;
import android.content.Intent;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Environment;
import android.provider.MediaStore;
import android.support.annotation.Nullable;
import android.support.v4.content.CursorLoader;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import java.io.File;
public class MainActivity extends AppCompatActivity {
private EditText width;//宽
private EditText height;//高
private EditText quality;//质量
private Button getImage;//获取图片
private Button show;//显示图片
private ImageView image;
private final int PICK_IMAGE = 100;
private Uri uri;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Bitmap bitmpa;
//bitmpa.compress(Bitmap.CompressFormat.JPEG, 70, );
width = findViewById(R.id.width);
height = findViewById(R.id.height);
quality = findViewById(R.id.quality);
getImage = findViewById(R.id.get_image);
show = findViewById(R.id.show);
image = findViewById(R.id.image);
getImage.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(Intent.ACTION_PICK);
intent.setType("image/*");
startActivityForResult(intent, PICK_IMAGE);
}
});
show.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String filePath = getRealPathFromURI(uri);
//二次采样
Log.i("TEST",filePath);
Bitmap bitmap = ImageUtil.scaleBitmap(filePath, Integer.parseInt(width.getText().toString()), Integer.parseInt(height.getText().toString()));
bitmap = ImageUtil.compress(bitmap, Integer.parseInt(quality.getText().toString()), new File(Environment.getExternalStorageDirectory(), "tmp2.jpg"));
image.setImageBitmap(bitmap);
//BitmapFactory.de
//质量压缩
//展示
}
});
}
private String getRealPathFromURI(Uri contentUri) { //传入图片uri地址
String[] proj = { MediaStore.Images.Media.DATA };
CursorLoader loader = new CursorLoader(this, contentUri, proj, null, null, null);
Cursor cursor = loader.loadInBackground();
int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
cursor.moveToFirst();
return cursor.getString(column_index);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
if(requestCode == PICK_IMAGE) {
if(resultCode == RESULT_OK) {
//图片uri
uri = data.getData();
}
return;
}
super.onActivityResult(requestCode, resultCode, data);
}
}
工具类ImageUtil
package com.example.image;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Environment;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
public class ImageUtil {
//图片二次采样
public static Bitmap scaleBitmap(String filePath, int width, int height) {
//进行两次decode
//第一次decode,只解析bitmap的宽高信息
//缩小图片大小, 降低内存占用
BitmapFactory.Options opts = new BitmapFactory.Options();
//指定只解析bitmap的边界信息,不加载bitmap到内存中
opts.inJustDecodeBounds = true;
BitmapFactory.decodeFile(filePath, opts);
//宽高信息
//1920 1080
//256 256
//opts.outWidth;
//opts.outHeight;
//通过图片的真实宽高信息 和 需要的宽高比,产生一个比例
opts.inSampleSize = Math.max(opts.outHeight / height, opts.outWidth / width);
//第二次加载图片: 真正加载图片
opts.inJustDecodeBounds = false;
Bitmap bitmap = BitmapFactory.decodeFile(filePath, opts);
return bitmap;
}
//tup质量压缩: 只改变文件大小,基本不改变内存占用
public static Bitmap compress(Bitmap bitmap, int qual, File output) {
Bitmap result = bitmap;
try {
//缩放后的
//bitmap.compress(Bitmap.CompressFormat.JPEG, 100, new FileOutputStream(new File(Environment.getExternalStorageDirectory(), "tmp.jpg")));
//压缩后的,保存到output文件
bitmap.compress(Bitmap.CompressFormat.JPEG, qual, new FileOutputStream(output));
//再次解析压缩后的图片
result = BitmapFactory.decodeFile(output.getAbsolutePath());
} catch (FileNotFoundException e) {
e.printStackTrace();
};
return result;
}
}